Oracle 11g introduce new tool/utility called ADRCI known as ADR command line tool.
This tool allow user to interact with ADR ,check alert log, check health monitor(HM) status ,
Package incident and problem information into a zip file for send to Oracle Support. Etc.
No username/password need to log in to ADRCI, ADRCI interact with file system and ADR data is secured only by operating system permissions on the ADR directories.
adrci> show alert -tail 100 -f ( Similar to tail -100f )
Too list all the "ORA-" error run following command
In 11g alert file is saved in 2 location, one is in alert directory ( in XML format log.xml ) and
old style alert file in trace directory. Both these directory reside inside ADR HOME. ADR (Automatic Diagnostic Repository ) is a file system based directory structure outside of the database, So you can have access of diagnostic data even database is down.
New initialization parameter DIAGNOSTIC_DEST decide where to store ADR data ( i.e diagnostic data). In oracle 11g parameter background_dump_dest, core_dump_dest, user_dump_dest is replaced by DIAGNOSTIC_DEST. Even you set background_dump_dest, core_dump_dest, user_dump_dest it not going to used i.e. 11g ignore these parameters.
SQL> show parameter diagnostic_dest
NAME TYPE VALUE
diagnostic_dest string /u01/app/oracle
More Oracle Database 11g New Features